{"id":"F2006B06432","name":"AD/R22/27 - Vertical Fin Attachments","slug":"ad-r22-27-vertical-fin-attachments","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":47825,"registerId":"commonwealth-F2006B06432-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/R22/27 - Vertical Fin Attachments","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nRobinson R22 Series Helicopters\n\nAD/R22/27 Vertical Fin Attachments 11/86 DM\n\nApplicability: All models fitted with vertical fin to horizontal stabilizer attachment brackets which have exceeded 500 hours time in service.\n\nRequirement: 1. Check the lower vertical fin for looseness of attachment which could indicate possible incipient failure of the attachment brackets.\n\n    2. Remove the lower vertical fin and\n\n    (a) visually inspect for fretting on the faying surfaces in the vicinity of the attachment bolts;\n\n    (b) inspect the fin attachment brackets in the horizontal stabilizer for cracking in the vicinity of the fin attachment bolts using a dye penetrant technique in accordance with ANO 108.10.\n\nCompliance: For para 1: At each daily inspection, until inspected in accordance with para 2.\n\nNote: This inspection may be accomplished by the pilot-in-command, in which case the precise A.D. reference shall be entered in a certification made on the Maintenance Release coincident with that for the daily inspection.\n\nFor para 2: Prior to exceeding 25 hours time in service after 22 September 1986, and thereafter at each issue of a new Maintenance Release.\n\nBackground: There have been two reported instances of cracking in the vertical fin attachment brackets, one of which caused an accident when the fin separated in flight.","sortOrder":0}],"analysis":{"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1061},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific airworthiness defect (cracking in vertical fin attachment brackets). It has not expanded beyond its original purpose of preventing structural failure in Robinson R22 helicopter tail sections."},"complexity_factors":["Technical aviation terminology requires domain knowledge (faying surfaces, dye penetrant, Maintenance Release)","References external technical standard ANO 108.10 without reproducing its content","Specific hour-counting thresholds (500 hours trigger, 25 hours compliance window)","Conditional compliance path (daily checks until detailed inspection completed)"],"plain_english_summary":"This rule mandates inspections of the brackets that attach the R22’s vertical tail fin to the horizontal stabilizer for helicopters with over 500 flight hours. It requires preflight looseness checks by pilots and a more thorough removal, fretting check and dye‑penetrant crack test by maintenance before further use or after a Maintenance Release.\n\nIt matters because a bracket failure has already caused a tail‑fin loss and crash; the inspections prevent that catastrophic failure."}},"importantCases":[],"_links":{"self":"/api/acts/ad-r22-27-vertical-fin-attachments","history":"/api/acts/ad-r22-27-vertical-fin-attachments/history","analysis":"/api/acts/ad-r22-27-vertical-fin-attachments/analysis","conflicts":"/api/acts/ad-r22-27-vertical-fin-attachments/conflicts","importantCases":"/api/acts/ad-r22-27-vertical-fin-attachments/important-cases","documents":"/api/acts/ad-r22-27-vertical-fin-attachments/documents"}}